audio config

DO NOT USE -ac 1 even with monaural audio as you’ll get lots of errors like

non-monotonous DTS in output stream 0:1;

-c:a libmp3lame -ar 44100

encode audio as MP3 with a 44.1 kHz sampling frequency (passing audio up to about 22 kHz, which is CD-quality).

list PulseAudio devices

pactl list sources

control audio sources

pavucontrol

video config explained

-framerate 10 -f x11grab -i :0.0+0,0 screengrab at 10 fps, starting in the upper left hand corner, send a 1024x720 pixel video.
If your screen resolution is more than 1024x720, there would be unsent regions at the bottom and/or right side.